Electromagnetically actuated fuel pump

ABSTRACT

AN ELECTROMAGNETICALLY ACTUATED FUEL PUMP COMPRISING A PISTON WHICH DELIVERS FUEL TO AN OUTLET CHAMBER PROVIDED WITH A FLEXIBLE WALL, AN OUTLET FOR CONNECTION TO A CARBURETOR, AND A SECOND OUTLET FOR CONNECTION TO THE SUPPLY TANK, SAID SECOND OUTLET BEING CONTROLLED BY A VALVE RESPONSIVE TO A PREDETERMINED MINIMUM PRESSURE   IN THE OUTLET CHAMBER. AN ELECTROMAGNETIC COIL ENCIRCLES THE PISTON CHAMBER AND AN ENERGIZING CIRCUIT IS CARRIED IN A SHELL ATTACHED TO THE OUTLET CHAMBER.

Jan. 19,1971 c. L. ROUQUETTE 3,556,634

ELECTROMAGNETICALLY ACTUATED FUEL PUMP Filed Dec. 150. 1968 2 Sheets-Sheet '1 Jan. '19, 1971 I c. L.--Rou'QuE'rT|-: ELECTROMAGNETICALLY LCTUA'IED rum. mar

mad Dec, so, 1968 2 Shgts-Sheet z United States Patent 3,556,684 ELECTROMAGNETICALLY ACTUATED FUEL PUMP Clement L. Rouquette, Puteux, France, assignor to S.E.V.-Marchal Filed Dec. 30, 1968, Ser. No. 787,775 Claims priority, applicatitrgoFrance, Jan. 3, 1968, 3 Int. Cl. F04b 17/04, 49/08 U.S. Cl. 417-307 4 Claims ABSTRACT OF THE DISCLOSURE SUMMARY OF THE INVENTION Many automobiles use fuel pumps for supplying fuel under a predetermined maximum pressure to a carburetor which supplies the cylinder of the motor. When mechanically controlled pumps are used for this purpose, particularly in the case of pumps controlled by a cam driven from the motor, the flow of fuel delivered by the pump is necessarily dependent on the rotational speed of the motor, so that during starting, the motor is less than perfectly supplied. Moreover, in the case of such pumps the mechanical control requires that the body of the pump be placed in close proximity to the motor block, which is undesirable from the point of view of properly cooling the pump.

Pumps have already been suggested which are electromagnetically controlled and which comprise a slida'ble piston made of a magnetic material, the movement of this piston being controlled by an electro-magnet in one direction and a return-spring in the other. Such an elec trical pump has the advantage of delivering a supply of fuel which is independent of the speed of the motor. Moreover, it may be located at some distance from the motor block, so that it may be easily cooled. However, the operation of this pump, which involves the reciprocation of a piston in a cylinder, produces an intermittent supply of fuel, with strong pressure and exhaust pulses, which is quite disadvantageous when supplying a carburetor downstream of the pump.

It is the purpose of the present invention to alleviate the above disadvantages which are inherent in pumps of known types.

It is therefore an object of the present invention to provide as a new article of manufacture an electrical pump which may be used to supply the internal combustion engines of automotive vehicles, which pump comprises on the one hand a cylindrical body encircled by a coaxial electromagnetic coil, which coil is energized by a square wave voltage, the body of the pump being provided with two valves, one of which controls the inlet and the other the outlet of the pump, with the first valve closing and the second opening when a pressure is created inside the pump and on the other hand a piston made of a magnetic material slidably mounted inside the pump body, the piston being spring-biassed in a direction opposite to the one in which it is attracted by the said coil, and carrying on the inlet side a valve which closes when the piston is attracted by the coil. This pump 1s p CC essentially characterized by the fact that the fuel being pumped, which passes out through the valve in the outlet zone of the pump, is delivered into a chamber having a wall formed by an elastic membrane, with the outlet pipe opening into said chamber and a return passage to the supply tank provided with a spring loaded valve responsive to a predetermined minimum pressure also opening into said chamber.

In a preferred embodiment of the invention, the elastic membrane is made of rubber coated cloth and is placed between the outlet chamber and an air cushion. The valve in the return passage leading to the supply tank is adjustable. Advantageously the electromagnetic coil which encircles the pump body is supplied through a transistor circuit the components of which are mounted on a framework attached to the outlet chamber, which framework is sufficiently open to the air to ensure adequate cooling of the pump.

It has been found that, in the device according to the invention, the interposition of an outlet chamber having an elastic membrane makes it possible to attenuate the pulses in the flow of fuel. Moreover, the presence of said pressure responsive valve in the return passage leading to the tank also makes it possible to limit the range of pressures obtained, so that the membrane and the valve cooperate to equalize the pressure delivered by the pump.

Moreover, the adjustment of the spring-loaded pressure responsive valve makes it possible to determine the maximum fuel pressure delivered by the pump. It follows that a single pump of a standard type may be used to supply carburetors of different types requiring different maximum pressures.

Finally the position which is preferably adopted for the transistor circuit which controls the pump is particularly advantageous from the point of view of the cooling of this circuit, for this circuit is in the output zone of the pump and the calories produced by the operation of the circuit may thus be carried off by the fuel pumped on. It should also be noted that the cooling of the circuit is independent of the output of the pump, since even the pump is producing no net output, the circulation of fuel through the outlet chamber continues at its normal rate because of the return passage leading to the supply tank. There is thus a cooperation between the location of the control circuit for the coil and the existence of the valved return passage to the supply tank.

In order that the invention may be better understood, one embodiment thereof will now be described, purely by way of example, with reference to the accompanying drawings, in which:

FIG. 1 is an axial section taken through an electric pump according to the invention, and

FIG. 2 shows the electrical control circuit through which the pump of FIG. 1 is supplied.

Referring now to the drawing, it will be seen that reference numeral 1 indicates the body of the pump which is encircled by a coaxial electromagnetic coil 2. A steel piston 3 is slidably mounted in the body 1 and biassed upwardly (when the pump is positioned as shown in FIG. 1) by a spring 4 which is supported at its lower end. Upward movement of the piston is resisted by a spring 4a, and the piston is pierced by a passage 5, at the top of which is a conical valve member 6 which closes against the seat 7 and is not spring-biassed.

An inlet passage 8 is located at the top of the pump body and connects it to a supply tank. This passage 8 opens into a chamber having an outlet controlled by a conical valve member 9 biassed against its seat 10 by a spring 11. At the lower end of the pump body is a valve member 12 biassed against its seat 13 by a spring 14. The valve member 9 closes when the pressure inside the central chamber in the pump body becomes greater than atmospheric, at which time the valve mem ber 12 closes. The valve member 12 controls the opening connecting the central chamber in the pump body, in which the piston 3 travels, to an outlet chamber 15. This chamber is provided near its lower end with an elastic membrane 16, the edges of which are gripped between two parts of a shell fixed to the pump body. On the side of the membrane opposite to the outlet chamber 15 is an air cushion 18 imprisoned between the membrane 16 and a part 18 of the shell. The outlet passage 19 leads from the outlet chamber 15 to the carburetor of the motor. Another passage 20 also leads from the outlet chamber 15 and is provided with calibrated valve comprising a ball 21, a spring 22, and a regulating screw 23. The passage 20 is connected, through the calibrated valve, to a passage 24 which is in communication with the supply tank.

Beneath the part 18 of the shell is a compartment 25 made of a material which is a good conductor of heat, as is the part 18 itself. Inside this compartment 25 are the electrical components of the circuit shown schematically on FIG. 2. The assembly of these components is schematically represented in FIG. 1 by the block 26. The compartment 25 is protected by a casing 27 provided at its bottom with ventilating holes 28.

The supply circuit for the coil 2 of the device which has just been described is shown in FIG. 2. It will be seen that this circuit is connected across the battery 29 of the vehicle. A transistor 30 is interposed between the positive pole of the battery 29 and one end of a coil 31, the other end of which is connected to the negative pole of the battery. A switch 36 is positioned between the battery 29 and the transistor 30. The base of the transistor 30 is connected to one of the ends of a coil 32, the other end of which is connected to the positive pole of the battery 29. The coils 31 and 32 are positioned to be mutually inductive and constitute a unit which serves as the electromagnetic coil 2 of the pump, shown in FIG. 1. By way of example, the coil 31 may have 650 turns, when the coil 32 has 180. Moreover, a resistance 33 is positioned between the collector and the emitter of the transistor 30. A resistor 35 is connected between the base of the transistor 30 and the negative pole of the battery 29. A condenser 34 is connected in parallel across the terminals of the resistance 35.

The operation of this device is as follows: When the switch 3 6 is closed, that is to say, in practice, when the ignition key is turned, the transistor 30, having a positively charged base, permits current to pass to the coil 31, which induces a current in the coil 31. This produces a voltage at the base of the transistor 30 which prevents the transistor 30 from remaining conductive. The current in the coil 31 is then cut off and the system becomes inactive until the base of the transistor 30 attains a voltage which permits it to become conductive again. It will be seen that this produces an intermittent energization of the coil 31. It follows that the coil 2 is supplied by a square wave current. It should be noted that the condensor 34 prevents disadvantages resulting from the interruption of the current in the coil 31 and the resistance 33 prevents surges at the terminals of the transistor 30.

When the coil 2 is energized, the piston 3 is drawn toward the bottom by the magnetic field of the coil, compressing the spring 4. The passage 5 is filled with fuel and the valve 12 is closed by the spring 14. The movement of the piston toward the bottom increases the pressure in the passage 5, thus closing the valve 6 and opening the valve 12. The movement of the piston toward the bottom enlarges the space between the valves 6 and 9, producing a reduced pressure behind the valve 9 and causing it to open. The fuel which is brought to the 4 pump by the passage 8 then passes through the valve 9 and enters the space between the valves 9 and 6.

When the coil 2 is de-energized, the electromagnetic force which acts on the piston 3 disappears and the piston is then forced upwardly in the pump body by the spring 4. In the course of this movement the valve 12 is closed by its spring 14, since the high pressure due to the descent of the piston 3 disappears. Moreover, the space between the valves 9 and 6 decreases, so that the valve 9 is closed by its spring 11 and the valve 6 opens in response to the increased pressure resulting from the decrease in the size of said space. The fuel, which entered this space during the preceding step, now passes into the passage 5, that is to say, the space between the valves *6 and 12. The pump is then returned to its original position and is ready for the start of a new cycle.

The fuel forced into the outlet chamber 15 during the first step leaves that chamber through the passages 19 and 20. The passage 19 leads to the carburetor of the motor which is to be supplied and the passage 20 is connected by the tube 24 to the supply tank. When the pressure within the chamber 15 reaches its maximum value, which corresponds to normal operation of the carburetor downstream therefrom, the ball 21 of the valve controlling the passage 20 is pressed back. By adjusting the pressure on the spring 22 by turning the screw 23, the user can regulate the maximum pressure which may be attained in the outlet passage 19. Moreover, when fuel is being pumped out, the elastic membrane 16, flexes under the pumping pressure so as to decrease the maximum pressure attained during the compression stage of the cycle. This elasticity is made possible by a cushion of air in the space 17. It will thus be seen that the combined effect of the return to the tank and the elasticity of the membrane 16 makes it possible to damp the fluctuations in the pressure produced by the pump. It should, moreover, be noted that the location of the electrical circuit 26 in its shell 25, which is a good conductor of heat and well ventilated, makes it possible to easily dissipate the heat produced in the circuit by the Joule effect. This part of the pump is particularly well cooled by the flow of fuel being pumped out, which flow is always constant, regardless of the quantity passing through the outlet passage 19, because the quantity of additional fuel which is not supplied to the passage 19 is returned to the tank through the passages 20 and 24. The device according to the invention thus offers a combination which permits the electrical circuit to be very well cooled. Finally, ventilating holes 28 are provided in the shell 27 to cool the compartment 25.

An additional advantage of the pump according to the invention is that it permits the elimination of vapor through the return to the tank which might form vapor locks in the passages leading to the carburetor. In effect, this vapor returns to the tank through the passages 20 and 24 to the extent that its pressure is greater than the pressure for which the valve comprising the ball 21 and spring 22 is set.

It will of course be appreciated that the foregoing example has been given purely by way of illustration and may be modified as to detail without thereby departing from the basic principles of the invention.

What is claimed is:

1. In an electromagnetically actuated fuel pump for pumping fuel from a fuel tank to a carburetor, which pump comprises a piston chamber having an inlet for connection to said tank and an outlet, a piston comprising magnetic material slidable in said piston chamber, an electrically energizable coil positioned to move said piston toward said outlet, and resilient means for returning said piston in the opposite direction when said coil is de-energized, the improvement which comprises a pressure-responsive valve in said outlet, an outlet chamber connected to said piston chamber by said outlet, a transistorized electrical circuit for intermittently energizing said coil, said circuit being mounted in a shell spaced by said outlet chamber from the remainder of said pump, a flexible diaphragm constituting at least part of one wall of said outlet chamber, a first outlet passage from said outlet chamber adapted to be connected to said carburetor, a second outlet passage from said outlet chamber adapted to be connected to said fuel tank, adjustable pressure-responsive valve means in said second outlet passage which permits fuel to enter said second passage when the pressure in said outlet chamber exceeds a predetermined minimum, a stationary valve in said inlet, and a valve carried by said piston which is movable toward and away from said stationary valve and which, when closed, acts as the face of said piston, each of said movable and stationary valves comprising a seat and a valve member mounted to seal against said seat when the pressure on the outlet side of that valve is greater than the pressure on the inlet side thereof.

2. A fuel pump as claimed in claim 1 in which said diaphragm separates said outlet chamber from a closed chamber containing a compressible gas.

References Cited UNITED STATES PATENTS 700,449 5/ 1902 Spencer 10342 2,533,164 12/1950 Dickey et al 10353X 2,669,186 2/1954 Parker 103-53 3,381,616 5/1968 Wertheimer et al 103-53 ROBERT M. WALKER, Primary Examiner US. Cl. X.R. 

